D12320VF25IV Datasheet, PDF (858/1304 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 19 ROM
19.18.2 RAM Overlap
An example in which flash memory block area EB1 is overlapped is shown below.
H'00000
EB0
H'01000
EB1
H'02000
EB2
H'03000
EB3
H'04000
EB4
H'05000
EB5
H'06000
EB6
H'07000
EB7
H'08000
This area can be accessed
from both the RAM area
and flash memory area
Flash memory
EB8 to EB11
H'3FFFF
On-chip RAM
H'FFDC00
H'FFEBFF
H'FFFBFF
Figure 19.45 Example of RAM Overlap Operation
Example in which Flash Memory Block Area EB1 is Overlapped
1. Set bits RAMS, RAM2, RAM1, and RAM0 in RAMER to 1, 0, 0, 1, to overlap part of RAM
onto the area (EB1) for which real-time programming is required.
2. Real-time programming is performed using the overlapping RAM.
3. After the program data has been confirmed, the RAMS bit is cleared, releasing RAM overlap.
4. The data written in the overlapping RAM is written into the flash memory space (EB1).
Notes: 1. When the RAMS bit is set to 1, program/erase protection is enabled for all blocks
regardless of the value of RAM2, RAM1, and RAM0 (emulation protection). In this
state, setting the P or E bit in flash memory control register 1 (FLMCR1) will not cause
a transition to program mode or erase mode. When actually programming a flash
memory area, the RAMS bit should be cleared to 0.
Rev.6.00 Sep. 27, 2007 Page 826 of 1268
REJ09B0220-0600